Over the many centuries that sewers and other drain pipes have been placed underground, they have been generally subject to ultimate and often premature failure due to blockage and/or damage, incurring heavy ongoing repair costs to homeowners, building owners and public utility agencies. Usually such failure is due to the invasion of roots of trees and other vegetation in a manner that is not generally well understood.
It is a popular misconception that root-related drain-pipe problems are caused by prior failure such as physical damage, e.g. cracked pipes, or faulty workmanship at the joints. Actual experience and testing have shown that roots, in their continuous forward thrust to spread and expand in the relentless search for water, often penetrate conventional drain pipe connectors that were correctly installed and otherwise intact.
This penetration usually leads to actual damage due to expansion of the roots, i.e. cracking, which then accelerates further root invasion, requiring frequent clean-out, and ultimately total blockage requiring costly digging-up and repair/replacement.